Process for producing a c6-c16 normal alpha-olefin oligomer having a pour point below about- f.

ABSTRACT

OLIGOMERS OF NORMAL-C6-16 ALPHA-OLEFINS USEFUL AS LUBRICANTS CAN BE MADE BY REACTING C6-16 NORMAL-ALPHAOLEFINS OR MIXTURE THEREOF AT A TEMPERATURE OF FROM ABOUT 10-60* C. USING A WATER PROMOTED BORON TRIFLUORIDE CATALYST IN WHICH BORON TRIFLUORIDE IS USED IN MOLAR EXCESS OF THE WATER. PREFERABLY, ADDITIONAL BORON TRIFLUORIDE IS INJECTED INTO THE REACTION LIQUID PHASE DURING THE COURSE OF THE OLIGOMERIZATION. STABILITY OF THE RESULTANT PRODUCT IS IMPROVED BY CATALYTIC HYDROGENATION. THE PRODUCTS HAVE A LOW POUR POINT AND HIGH VISCOSITY INDEX.

United States Patent O 3,763,244 PROCESS FOR PRODUCING A C C NORMAL ALPHA-OLEFIN OLIGOMER HAVING A POUR POINT BELOW ABOUT -50 F. Ronald L. Shubkin, Oak Park, Micl1., assignor to Ethyl Corporation, Richmond, Va. N Drawing. Filed Nov. 3, 1971, Ser. No. 195,441 Int. Cl. C07c 9/00, /02 US. Cl. 260-676 R Claims ABSTRACT OF THE DISCLOSURE Oligomers of normal-C alpha-olefins useful as lubricants can be made by reacting C normal-alphaolefins or mixture thereof at a temperature of from about 10-60" C. using a water promoted boron trifiuoride catalyst in which boron trifiuoride is used in molar excess of the water. Preferably, additional boron trifiuoride is injected into the reaction liquid phase during the course of the oligomerization. Stability of the resultant product is improved by catalytic hydrogenation. The products have a low pour point and high viscosity index.

BACKGROUND Olefin oligomers have been used in the past as synthetic lubricants. Seger et al., US. Pat. 2,500,161, describes a process for making such synthetic lubricants by polymerizing l-olefins using a lead tetraacetate catalyst. Garwood, US. Pat. 2,500,163, describes similar synthetic lubricants made by polymerizing l-olefins using phosphorus sulfide catalysts. Hydrogenation of such olefin oligomers to improve their stability is also well known. Reid, US. Pat. 2,360,446, describes blends of mineral oil and synthetic olefin polymers in which the olefin polymer is hydrogenated to improve its resistance to oxidation and chemical change. Hamilton et al., US. 3,149,178, describe oligomers made from alpha-olefins using peroxide, Friedel-Crafts or thermal catalysis. In accordance with Reid, their stability is improved by hydroganation. As discussed in Hamilton et al., this hydrogenation, though improving the oligomer stability, unfortunately causes a sharp increase in pour point. In Hamilton et al. this problem was minimized by distilling out the dimer content of the olefin oligomer to obtain a dimer-free product. It has now been discovered that the increased pour point of hydrogenated oligomers can be avoided without the necessity of resorting to a distillation step to obtain dimer-free product. By the present invention, oligomers of normalalpha-olefins are made which have a pour point after hydrogenation which is not substantially higher than that exhibited by the same oligomer from which dimer has been distilled.

An object of the invention is to provide an improved synthetic lubricant. A further object is to provide a lubricant having a high viscosity index. Another object is to provide a lubricant having a very low pour point. A still further object is to provide a process for making such synthetic lubricants which does not require removal of olefin dimer in order to achieve the required low pour point.

SUMMARY The above and other objects of the present invention are accomplished by providing a process for oligomerizing a C normal-alpha-olefin monomer or mixtures thereof by reacting the olefin monomer at a temperature of from about 10-60 C. using as a catalyst a water promoted boron trifiuoride. The amount of boron trifiuoride used in the oligomerization is in molar excess of the amount of Water promoter. A highly preferred means of accomplishing this is to add boron trifiuoride to the olefin Patented Oct. 2, 1973 monomer reaction mixture containing the water cocatalyst until the oligomerization initiates and then to continue to add boron trifiuoride during the course of the oligomerization. Following the oligomerization stage, the catalyst is removed and the reaction product hydrogenated catalytically to produce useful synthetic lubricant compositions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention is a process for producing a C normal-alpha-olefin oligomer having a low pour point and high viscosity index suitable for use as a synthetic lubricant, said process comprisin reacting a C normal-alpha-olefin or mixture of such olefins at a temperature of from about 10-60" C. using a catalytic amount of boron trifiuoride as a catalyst and a promoter amount of a water co-catalyst, said boron trifiuoride being present in a molar excess of said water thereby producing an olefin oligomer. A further preferred embodiment includes the step of catalytically hydrogenating said olefin oligomer to form a substantially saturated product.

The olefins used in making the oligomer are straightchain monoolefinically unsaturated hydrocarbons in which the olefinic unsaturation occurs at the 1- or alpha-position of the straight carbon chain. Such alpha-olefins are commercially available and can be made by the thermal cracking of paratfinic hydrocarbons or by the well-known Ziegler ethylene chain growth and displacement on triethyl aluminum. Superior lubricants result when the olefin monomers contain from about 6-16 carbon atoms. Individual olefins may be used as well as mixtures of such olefins. Examples of such olefins are l-hexene, l-heptene, 1-octene, l-nonene, l-decene, l-dodecene, l-hexadecene and l-tetradecene. The more preferred normal-alphaolefin monomers are those containing about 8-12 carbon atoms. The most preferred olefin monomer is l-decene.

When mixtures of alpha-olefins are used it is preferred that the mole average chain length be from about 8l2 carbon atoms. Mole average chain length is determined by multiplying the number of carbon atoms of each specie in the mixture by the mole fraction of that specie present and then adding the products. For example, the mole average chain length of a mixture of one mole of 1- hexene, 2 moles of l-octene, 6 moles of l-decene, and one mole of l-dodecene is (0.1 6)+ (0.2 8)+(0.6 l0) +(0.1 X 12), or 9.4.

The amount of water used to conduct the polymerization need only be a promoter amount. This is the amount which when used together with boron trifiuoride causes the reaction to proceed at a reasonable rate. This is readily determined experimentally because boron trifiuoride alone is not an effective catalyst under the present reaction conditions. Good results are obtained using from about 0.05 to about 10 parts of water per parts of normal-alpha-olefin monomer. A preferred range is from about 0.1 to 5 parts per 100 parts of monomer.

The amount of boron trifiuoride used in the process should be a catalytic amount. This is an amount which when used in the presence of the water co-catalyst will cause the reaction to proceed at a reasonable rate. A useful range of boron trifiuoride is from about 0.15 to 15 parts per 100 parts of olefin monomer. A preferred range is from about 0.3 to about 7 parts per 100 parts of olefin monomer.

The actual catalyst specie is believed to form from the interaction between boron trifiuoride and the water cocatalyst. For this reason, whenever reference is made to the use of a water-promoted boron trifiuoride or that the reaction is carried out in its presence, it is meant that the actual catalyst specie that is used and in the presence of which the reaction is conducted in the specie that forms in the oligomerization system when boron trifluoride and the water co-catalyst are added to the system in the manner prescribed. In order to form the proper catalyst specie which is necessary to achieve the objectives of the present invention it is required that the boron trifluoride be added to the reaction system in molar excess of the water. When less than a molar excess is used, either the oligomerization does not proceed at all under the reaction conditions, or proceeds in a different manner producing an oligomer which does not have a satisfactory pour point after hydrogenation without the distillation step disclosed in US. Pat. 3,149,178.

The molar excess of boron trifluoride in the system can be achieved in a number of ways. One way is to add the water co-catalyst to the alpha-olefin monomer and then add a molar excess of boron trifluoride in a closed system. The molar excess of boron trifluoride is assured by conducting the reaction under a boron trifluoride pressure of from about 5500 p.s.i.g.

A preferred way to conduct the oligomerization is to merely inject boron trifluoride during the course of the oligomerization into the liquid reaction media to which has been added the water co-catalyst. The boron trifluoride may be continuously bubbled into the reaction phase during the course of the reaction or may be injected periodically. The system need not be maintained under pressure and, in fact, good results are achieved by carrying out the oligomerization at atmospheric pressure, allowing excess boron trifluoride gas to vent. It is generally preferred when using this supplemental boron trifluoride technique to conduct the oligomerization under moderate pressure of from about 1-15 p.s.i.g. Whenever the pressure exceeds the desired limit due to the injection of additional boron trifluoride into the liquid phase, the vapor phase is vented at a controlled rate to maintain the desired pressure, either atmospheric or superatmospheric. The vent gas, whether the reaction is carried out under superatmospheric or atmospheric pressure, consists mainly of boron trifluoride which may be readily recycled back into the liquid reaction phase so that in effect a closed boron trifluoride loop is formed.

The oligomerization is readily conducted by placing the normal-alpha-olefin in a reaction vessel and adding to it the water co-catalyst and boron trifluoride. The water co-catalyst may be in the form of a preformed boron trifluoride water complex or may consist only of the water. The addition of water in the form of a boron trifluoride complex is not sutlicient in itself to achieve the low pour point oligomers of this invention. Such complexes do not normally contain suflicient boron trifluoride to provide the required molar excess. Oligomerizations attempted in this manner usually do not react under the prescribed reaction conditions, and when they do, lead to products that when hydrogenated have an unacceptably high pour point. This failure of the usual boron trifluoride-water complex to yield the desired product will be shown in later examples. In order to achieve the desired results, it is required to add boron trifluoride in addition to the amount normal- 1y contained in a preformed water-boron trifluoride complex. As explained previously, this may be accomplished by adding boron trifluoride to a closed oligomerization system or by injecting it into the liquid reaction phase during the course of the oligomerization. For this reason, it is not necessary to add the water co-catalyst as a preformed boron trifluoride complex. One practical advantage of so doing is that when the water is added in the form of a boron trifluoride complex and additional boron trifluoride is then introduced into the system the desired oligomerization reaction will initiate in a shorter time period than when the water is added alone followed by the injection of boron trifluoride.

The oligomerization reaction generally initiates shortly after the amount of boron trifluoride added to the system is in molar excess over the water co-catalyst. The reaction should be allowed to proceed until a good conversion of monomer to oligomer is achieved. In most cases this is accomplished in from about 1-4 hours. Conversion of the normal-alpha-olefin to oligomer is generally in excess of percent. In fact, in most cases there is so little monomer left in the reaction mixture (on the order of 13 percent) that it need not even be distilled out prior tocatalytic hydrogenation. In others words, the entire reaction mass can be merely treated to remove oligomerization catalyst and then hdyrogenated to yield a useful lubricant. If even a small amount of unconverted monomer is undesirable because of, for example, flash point limits on the product, it can readily be distilled out of either the oligomerization reaction product or the final hydrogenated lubricating oil.

The reaction temperaturue should be high enough such that the reaction initiates and proceeds at a good rate, but not so high such that the final hydrogenated product has an unsatisfactory pour point. A useful temperature range is from about 10-60 C. Excellent results are generally achieved by maintaining the oligomerization reaction within a temperature range of from about 20-30 C. during at least the major portion of the reaction period.

After the oligomerization is complete the catalyst can be removed by conventional methods. The lower liquid catalyst phase can be merely removed and added to another normal-alpha-olefin charge and a subsequent oligomerization carried out in the same manner as the first, that is, by injecting additional boron trifluoride into either a vented or closed system. Alternatively, the upper oligomer phase can be drawn off leaving the catalyst phase in the reaction vessel and a new charge of normal-alpha-olefin monomer added to this same reaction vessel. Residual catalyst in the oligomer can be washed out with Water. It is preferable to dry the oligomer prior to catalytic hydrogenation.

The process does not require a solvent, although an inert solvent can be used if desired. Saturated aliphatic hydrocarbons containing from about 5-10 carbon atoms are satisfactory, such as pentane, hexane, heptane, and the like. The lower hydrocarbon solvents such as pentane can also function to control reaction temperature. The preferred way to conduct the reaction is in the absence of solvent since this simplifies product recovery.

The oligomers can be hydrogenated by standard means. It is merely placed in a pressure vessel together with a hydrogenation catalyst and pressurized with hydrogen under hydrogenation conditions. Useful catalysts include platinum supported on charcoal, palladium supported on charcoal, Raney nickel, nickel on kieselguhr, copper, chromite, alumina supported copper and palladium, and the like. Pressures can vary over a wide range depending upon catalyst activity. A useful hydrogenation pressure range is from about 2000 p.s.i.g. Temperature can also vary widely depending upon catalyst and hydrogen pressure. A useful range is from about 50-300 C., especially from about ISO-200 C. The hydrogenation should be conducted until the product is substantially completely saturated. The degree of unsaturation can be monitored by determining iodine number. A satisfactory lubricant should have an iodine number below about 1.0, and preferably below about 0.2.

The synthetic oligomers made by the present invention have desirable lubricant properties. The absolute value of viscosity vary somewhat depending upon the number of carbon atoms in the starting monomer. Typical physical properties are:

Viscosity at 100 F. (cs.) 1055 Viscosity at 210 F. (cs.) 3-l5 Viscostiy index -160 Pour point F.) 50

An important feature of the present invention is that it results in a substantially saturated normal-alpha-olefin oligomer lubricant which has a pour point below about 50 C. without resorting to a distillation step to remove dimer, as taught by US. Pat. 3,149,178. The products having the above typical properties are obtained by merely conducting the oligomerization process in the manner prescribed without distilling out dimer. Of course, if it is desired to distill out the dimer to obtain a dimer-free product, this is not detrimental but generally unnecessary. Typical product composition is a hydrogenated substantially saturated oligomer of C normal-alpha-olefins consisting essentially of from about 210 weight percent dimer, about 5085 weight percent trimer, and the remainder tetramers and higher oligomers. It has been found that these particular compositions have the required low pour point property without subjecting them to distillation to obtain a dimer-free product.

The following examples serve to illustrate the manner in which the present process is carried out and also to compare the results obtained to those obtained from similar procedures outside the scope of the present invention. All parts are by weight unless otherwise indicated.

Example 1 This example shows that boron trifluoride alone is an ineffective catalyst.

In a reaction vessel equipped with stirrer and gas injection tube was placed 50 parts of l-decene. While stirring vigorously, boron trifluoride gas was injected into the liquid for 30 minutes at a temperature of 25 C. Stirring was continued for 3 hours. At this time, gas chrd matographic analysis showed that no reaction had occurred.

Example 2 This example shows the results obtained with a preformed boron trifluoride-water complex.

In a reaction vessel equipped with stirrer and cooling means was placed 50 ml. of l-decene and 0.5 ml. of a preformed boron trifluoride-water complex (1:1 mole ratio). After stirring for one hour at 2527 C., gas chromatographic analysis showed no reaction. An additional 1 ml. of the boron trifluoride-water complex was added and the mixture stirred for an additional hour at 25-27 C. Gas chromatographic analysis showed that 70 percent of the monomer had been converted to higher oligomers. Stirring was continued under these conditions for 16 hours, at which time the product analyzed:

Percent Monomer 3.6

Dimer 18.5

Trimer 77.9

Tetramer -1 Trace These results show that when a similar process is conducted not using the excess boron trifluoride the reaction is slow to start and yields a product having a large amount of undesirable dimer.

Example 3 This example illustrates the results obtained using a water-promoted boron trifluoride catalyst according to the method of the present invention.

In a reaction vessel equipped with stirrer, cooling means and gas injection tube was placed 200 parts of 1-decene and 025 part of water. While stirring, boron trifluoride gas was injected into the liquid phase. Temperature was maintained at 2535 C. by cooling. After 3 hours under the above conditions, the product was washed with dilute aqueous hydrochloric acid and then twice with 5 percent aqueous sodium carbonate. The product was dried over anhydrous calcium sulfate and filtered. After distillation to remove a trace of unreacted monomer the remaining product contained 6.5 percent dimer and the balance mainly trimer and some higher oligomers. Catalytic hydrogenation of the product yields a saturated synthetic lubricant having high viscosity index and low pour point.

6 Example 4 In the reaction vessel of Example 3 Was placed 200 parts of l-decene and 0.5 part of water. While stirring, boron trifluoride gas was injected into the liquid phase at 15-20 C. After about 15 minutes an exothermic reaction set in and the temperature rose to 25 C. Boron trifluoride injection was continued for one hour at 2030 C. and then the reaction mixture was washed with dilute aqueous hydrochloric acid and then with 5 percent aqueous sodium carbonate. It was dried over anhydrous calcium sulfate and filtered. The product contained only 2.6 percent dimer, the balance being trimer, tetramer and a small amount of higher oligomers. Catalytic hydrogenation at 200 C. and 1000 p.s.i.g. hydrogen for 6 hours in the presence of 10 parts of charcoal supported palladium gives a synthetic oligomer having high viscosity index and low pour point.

Example 5 In the reaction vessel of Example 3 was placed 200 parts of l-decene and 1 part of water. While stirring, boron trifluoride gas was injected into the liquid phase. Temperature remained at 17-20 C. for 25 minutes and then a reaction initiated and the temperature started to rise. Cooling was applied and over a 50-minute period the temperature gradually rose to 27 C. Temperature then began to drop, reaching 15 C. Stirring and boron trifluoride injection was continued for an additional hour. Product was washed with dilute aqueous hydrochloric acid and then with 5 percent aqueous sodium carbonate. After drying over anhydrous calcium sulfate the product was transferred to a hydrogenation autoclave. It was hydrogenated at 220 C. and 1250-1500 p.s.i.g. hydrogen, using 17.5 parts of kieselguhr supported nickel catalyst. Gas chromatographic analysis of the resultant product showed it to consist of 1.7 percent monomer, 4.4 percent dimer, 60.4 percent trimer and 33.5 percent tetramer. Its physical properties were as follows:

Viscosity 210 F. (cs.) 5.10 Viscosity 100 F. (cs.) 26.17 Viscosity 40 F. (cs.) 4846 Viscosity index 137 Pour point F.) --70 Example 6 1n the reaction vessel of Example 3 was placed 200 parts of a normal-alpha-olefin mixture (30.0 weight percent 1- hexene, 37.8 weight percent l-octene and 31.4 weight percent l-decene) and 1.0 part of water. The vessel was cooled in an ice bath while stirring and injecting boron trifluoride into the liquid phase. Temperature slowly dropped to 10 C. over a lO-minute period. It then rose slowly to 20 C. over a 30-minute period. The temperature then rose abruptly to C. in 3 minutes and then cooled to 17 C. Boron trifluoride injection was continued for an hour at room temperature. The mixture was then washed twice with 5 percent potassium carbonate and dried over anhydrous calcium sulfate. The product was hydrogenated at 220 C. and 1250 p.s.i.g. hydrogen for 10 hours using 19 parts of a kieselguhr supported nickel catalyst. The resultant oil was filtered and distilled up to 135 C. at 1.5 mm. Hg to remove light ends. Its physical prop erties were as follows:

Viscosity 210 F. (cs.) 4.09 Viscosity F. (cs.) 20.9 Viscosity 40 F. (cs.) 5863 Viscosity index 104 Pour point F.) -70 Example 7 This example illustrates the manner by which the process can be carried out in a closed system.

In an autoclave place 146 parts of l-decene and 1.5 parts of Water. Flush the vessel with nitrogen, seal, and while stirring, pressurize with boron trifluoride. Maintain temperature at 25-30 C. Increase boron trifluoride pressure gradually to 200 p.s.i.g. Vent the vessel and wash twice with water. Dry over activated alumina and then hydmgenate over a copper chromite catalyst to give a useful synthetic lubricant.

Example 8 The following example illustrates the process carried out with a closed loop boron trifluoride recycle.

A reaction vessel is fitted with a stirrer, cooling jacket, gas injection tube extending to the bottom of the vessel, a vent line through a constant pressure valve, a compressor in the vent line, and a conduit from the discharge side of the compressor connected to the inlet of the gas injection tube. In the vessel is placed a mixture of 10 parts l-hexene, 150 parts l-octene, 400 parts l-decene and 125 parts 1- dodecene. Then 10 parts of water is added and the vessel is closed and stirring started. Boron trifluoride gas is injected through the gas injection tube from an anhydrous boron trifluoride gas cylinder. The temperature is maintained between 25-30 C. The constant pressure valve in the vent line is set at 10 p.s.i.g. When the pressure reaches 10 p.s.i.g., the vent valve opens and allows gas to escape into the vent line at a rate which maintains the pressure in the vessel at 10 p.s.i.g. The escaping gas consists mainly of boron trifluoride and is compressed to about 15 p.s.i.g. and conducted back to the inlet of the gas injection tube. During the course of the reaction a small amount of make-up boron trifluoride from the gas cylinder is continuously added to the system in an amount such that there is a constant flow of gas through the boron trifluoride injection tube. The reaction is continued for 2 hours, at which time the addition of boron trifluoride is stopped and the reaction stirred for 30 minutes. The reaction mixture is then discharged to a wash vessel where it is washed twice with water and finally with 5 percent aqueous sodium carbonate. The resulting oligomer is dried by conducting it through an anhydrous calcium sulfate packed column. The dried product is placed in a high pressure hydrogenation autoclave and 50 parts of kieselguhr supported nickel hydrogenation catalyst is added. The autoclave is sealed, and while stirring, pressurized to 100 p.s.i.g. with hydrogen. The autoclave is then heated to 200 C. and hydrogen pressure gradually increased to 1500 p.s.i.g. Stirring is continued under these conditions for 6 hours, at which time the autoclave is cooled and vented, resulting in a saturated olefin oligomer having physical properties making it ideally suited as a synthetic lubricant.

The saturated oligomers of the present invention are useful as synthetic lubricants in such applications as automotive engines, diesel engines and in turbines including turbojet engines. They are especially useful under frigid conditions Where a low pour point is important. They may be used as the sole lubricant or may be blended with mineral lubricating oils or with other synthetic lubricants such as synthetic ester lubricants, e.g., di-2-ethylhexyl adipate, trimethylolpropane tricaproate, and the like. Properties of the lubricants are improved by inclusion of known lubricant additives such as zinc dialkyldithiophosphates, calcium aryl sulfonates, overbased calcium aryl sulfonates, barium phenates, barium oxide neutralized reaction products of phosphorus pentasulfide, and terpenes or high molecular weight olefins, 4,4 methylenebis 2,6 di-tertbutylphenol, dibutyl tin sulfide, dibutyl hydrogen phosphonate, tricresylphosphate, high molecular weight alkyl succinimides of ethylenepolyamines such as tetraethylenepolyamine, and the like. The following example illustrates the preparation of a lubricant suitable for use in spark ignited automotive engines.

Example 9 In a blending vessel is placed 10,000 parts of the hydro genated olefin oligomer prepared in the manner described in Example 7. To this is added 70 parts of zinc isobutylhexyl dithiophosphate. Overbased calcium dodecyl benzene sulfonate (base No. 300) in an amount to provide 0.4 percent calcium and 300 parts of an alkenyl succinimide of a crude tetraethylenepentamine mixture in which the alkenyl group has an average molecular weight of 900 are added. The mixture is stirred until homogeneous and filtered to give a useful synthetic lubricant for automotive spark ignited engines.

The above lubricant can also be used in diesel engine lubrication, although it would be generally desirable to eliminate the use of the alkenyl succinimide dispersant and increase the amount of calcium dodecyl benzene sulfonate.

The synthetic lubricants are also very useful as a base stock for preparing grease. These are made by adding a sufiicient amount, from about 5-25 percent, of a fatty acid soap to thicken the oil. Typical fatty acid soaps are lithium, sodium, and calcium salts of oleic acid, or crude mixtures containing such fatty acids.

The products also find use as functional fluids such as hydraulic fluid.

I claim:

1. A process for producing a C normal-alpha-olefin oligomer having a pour point below about -50 F. and consisting essentially of from about 2 to about 10 weight percent dimer and from about 50 to weight percent trimer, the balance being higher oligomers, suitable for use as a synthetic lubricant, said process comprising reacting a C normal-alpha-olefin or mixture of such olefins in a temperature range of from about l0-60 C. in the presence of about 0.05 to about 10 parts of water per parts of said normal-alpha-olefin and injecting boron trifluoride into said normal-alpha-olefin during the course of the oligomerization in an amount in excess of the amount soluble in said normal-alpha-olefin, to produce an olefin oligomer.

2. A process of claim 1 wherein said temperature range is from about 20-30" C.

3. A process of claim 1 wherein said olefin oligomer is hydrogenated under catalytic hydrogenation conditions to yield a substantially saturated product.

4. A process for producing a substantially saturated C normal-alpha-olefin oligomer having a pour point below about 50 F. and high viscosity index suitable for use as a synthetic lubricant, said process comprising (a) reacting in the liquid phase a C normal-alpha-olefin or mixture of such olefins Within a temperature range of from about 10 to about 60 C. in the presence of about 0.05 to about 10 parts of water per 100 parts of said normal-alpha-olefin while introducing boron trifluoride into said liquid phase in an amount in excess of the amount soluble in said normal-alpha-olefin thereby producing an olefin oligomer, and (b) hydrogenating said olefin oligomer under catalytic hydrogenation conditions to form a substantially saturated product.

5. A process of claim 4 wherein the mole average chain length of said C normal-alpha-olefin is from about 8-12.

6. A process of claim 4 wherein said normal-alphaolefin consists predominantly of l-decene.

7. A process of claim 4 wherein said temperature range is from about 20-30 C.

8. A substantially saturated olefin oligomer having a pour point below about 50 F. and high viscosity index, said oligomer consisting essentially of from about 2 to about 10 weight percent dimer and from about 50 to about 85 weight percent trimer, the balance being higher oligomers, suitable for use as a lubricant made by the process comprising (a) reacting a C normal-alphaolefin or mixture of such olefins at a temperature of from about 10-60 C. in the presence of about 0.05 to about parts of water per 100 parts of said normalalpha-olefin and injecting boron trifiuoride into said normal-alpha-olefin during the course of the oligomerization in an amount in excess of the amount soluble in said normal-alpha-olefin, thereby producing an olefin oligomer, and (b) hydrogenating said olefin oligomer under catalytic hydrogenation conditions to form a substantially saturated product.

9. An olefin oligomer of claim 8 wherein said temperature range is from about to about C.

10. An olefin oligomer of claim 8 wherein the mole average chain length of said normal-alpha-olefin mixture is from about 8-12.

11. A substantially saturated olefin oligomer having a pour point below about F. and high viscosity index suitable for use as a lubricant made by the process comprising (a) reacting in the liquid phase a C normalalpha-olefin or mixture of such olefins within a temperature range of from about 10 to about C. in the presence of about 0.05 to about 10 parts of water per 100 parts of said normal-alpha-olefin while introducing boron trifiuoride into said liquid phase in an amount in excess of the amount soluble in said normal-alpha-olefin thereby producing an olefin oligomer, and (b) hydrogenating said olefin oligomer under catalytic hydrogenation conditions to form a substantially saturated product.

12. An olefin oligomer of claim 11 wherein the mole average chain length of said normal-alpha-olefin mixture is from about 8-12.

13. An olefin oligomer of claim 11 wherein said normal-alpha-olefin consists predominantly of l-decene.

14. A hydrogenated oligomer of C normal-alphaolefins consisting essentially of from 2 to about 10 weight percent dimer and from about 50 to weight percent trimer, the balance being higher oligomers, said oligomer having a pour point below about 50 C.

15. A hydrogenated oligomer of claim 14 wherein the mole average chain length of said normal-alpha-olefins is about 8-12 carbon atoms.

References Cited UNITED STATES PATENTS 3,382,291 5/1968 Brennan 260-68315 3,149,178 5/1967 Hamiton et a1. 260683.9 2,360,446 3/1965 Ried 20819 2,270,303 1/1942 Ipatietf 260683.9 3,375,295 3/1968 Rowe 260683.15 2,938,855 5/1960 Mason et al. 260-68315 B DELBERT E. GANTZ, Primary Examiner I. M. NELSON, Assistant Examiner US. Cl. X.R. 

